Fortún Garcés (Arabic: فرتون بن قرسية‎, Fortoûn ibn Garsiya, d. after 925), called the One-Eyed or the Monk, was the king of Pamplona from 882 to 905.

He was the eldest son of King García Íñiguez, himself the son of king Íñigo Íñiguez Arista, the founder of the kingdom, and Fortún was to be the last king of the Arista dynasty.

Prince Fortún was taken prisoner by the Moors in 860 during the invasion of Emir Mohammed I of Córdoba and kept for the next 20 years. While a prisoner in Córdoba, his daughter Oneca Fortúnez married Abdallah ibn Mohammed, who would later succeed his father as Emir. He was released from captivity in 880 and returned to Pamplona, apparently accompanied by his daughter. He succeeded upon the death of his father at Ayhar in 882 in a battle against Emir Mohammed I.

Little is known of the remainder of his reign except the manner of its ending. In 905, an alliance of the Banu Qasi under Lubb ibn Mohammed, King Alfonso III of Asturias, and count Raymond I of Pallars brought about a successful coup in favor of the latter's nephew, Sancho Garcés, son of García Jiménez of "another part of the kingdom", forcing Fortún to retire as a monk to Leyra.

Fortún had several surviving children by his wife Oria, whose parentage has been subject to much speculation:

• Íñigo Fortúnez
• Aznar Fortúnez
• Blasco (Velasco) Fortúnez
• Lope Fortúnez
• Oneca Fortúnez, who married firstly Abdallah ibn Mohammed, Emir of Córdoba, and secondly her cousin Aznar Sánchez of Larraun, grandson of king García Íñiguez, becoming the mother of the future queens Toda Aznárez, wife of Sancho Garcés, and Sancha Aznárez, wife of king Jimeno Garcés, as well as grandmother of caliph Abd-ar-Rahman III.

Preceded by García Íñiguez

King of Pamplona 882–905

Succeeded by Sancho Garcés I